Document auth fix for 5.24.0+ (#2764)

Author: pwizla

docusaurus/docs/cms/configurations/admin-panel.md

@@ -285,6 +285,10 @@ Admin authentication uses session management by default for enhanced security.
 
 Session management provides enhanced security for authentication in Strapi applications by using short-lived access tokens paired with longer-lived refresh tokens. This approach reduces the risk of token theft and allows for more granular control over user sessions.
 
+:::caution Serve the admin panel over HTTPS
+Since v5.24.0, Strapi stores admin authentication data in secure, HTTP-only cookies. Browsers only accept and send these cookies over HTTPS connections, so attempting to access the admin panel via plain HTTP prevents the session cookie from being set and results in failed logins. Always expose the admin panel through HTTPS in production (for example, by placing Strapi behind a TLS-terminating proxy or load balancer). Local development continues to work with the default configuration because cookies are not marked as secure in that environment.
+:::
+
 Strapi's session management system supports both admin panel authentication and Content API authentication through the [Users & Permissions feature](/cms/features/users-permissions). The system provides:
 
 - Short-lived access tokens (typically 30 minutes) for API requests

docusaurus/docs/cms/faq.md

@@ -46,6 +46,15 @@ With the release of the Strapi 3.0 beta version a fundamental change occurred in
 
 Strapi has released the Admin & Permissions (RBAC - Role-Based Access Control) that does allow for some degree of control over what users can access within the admin panel and includes some field level permissions. You can also give roles specific permissions for things like content-types, single types, plugins, and settings.
 
+## Why does the admin login fail when I use HTTP instead of HTTPS?
+
+Starting from v5.24.0, the Strapi admin panel relies on secure, HTTP-only cookies to store session data. Browsers refuse to store or send these cookies over insecure HTTP connections, which means the admin login cannot complete if the panel is served without HTTPS. To restore access:
+
+- Terminate TLS in front of Strapi (for example with Nginx, Caddy, Traefik, a load balancer, or your cloud provider) and expose the admin panel through HTTPS.
+- Ensure the proxy forwards the appropriate headers (such as `X-Forwarded-Proto`) so Strapi can detect the secure connection.
+
+Local development using the built-in Strapi server continues to work because the development configuration does not set the cookies as secure.
+
 ## Why are my application's database and uploads resetting on PaaS-type services?
 
 If you used `--quickstart` to create your Strapi project, by default this uses the SQLite database. PaaS systems (Heroku, DigitalOcean Apps, Google App Engine, etc.) file systems are typically <ExternalLink to="https://devcenter.heroku.com/articles/dynos#ephemeral-filesystem" text="ephemeral"/> or read-only meaning that each time a dyno (container) is reset all filesystem changes are lost. And since both SQLite and local uploads are stored on the filesystem, any changes made to these since the last dyno reset will be deleted. Typically dynos are reset at least once a day, and in most cases multiple times per day or when new code is pushed to these services.